[Elecraft] K3 circuit breaker

[Mark N2QT]

My K3, SN 3091 has popped the 12v circuit breaker.  After resetting the breaker
 everything works well, full power out with about 16A draw at 14Vdc.

It has done this twice in the last week.  I have been working remotely so not present
to see if any other indications of a fault.  Has happened on 40M (which has an external 
antenna tuner) and 20M which has a resonant antenna.

Suggestions? 

Mark. N2QT